Genetics Of Mitochondria


Presentation Description

K.K.Chandel Department Of Genetics & Plant Breeding Junagadh Agri.. University JUNAGADH GUJ.


Presentation Transcript

PowerPoint Presentation:

Welcome Welcome 1

Genetics of Mitochondria:

Genetics of Mitochondria Dr. D.R.Maheta Assistant Professor Department of Genetics & Plant Breeding Junagadh Agricultural University, Junagadh (Gujarat) 362 001 Submitted by CHANDEL KAMLESH KUMAR M.Sc.Agril. (Genetics & Plant Breeding) 2011-2012 Submitted to 2

PowerPoint Presentation:


PowerPoint Presentation:

Introduction of Mitochondria Mitochondrial DNA (mtDNA) lies within the matrix, it appears in highly condensed structure called nucleoids . The mtDNA of most cells does not reside in a single location. 2. The number of mitochondria, nucleoids, and mtDNA molecules are variable. The mechanisms are not yet understood. 3. Mitochondria can fuse with each other as well as divide. 4. In general, mitochondria double in size and then divide in half in each cell generation. 5. The replication of mtDNA, and the division of the mitochondria are independent of the nuclear DNA and cell division. 6. Which mtDNA undergo replication seems to be determined at random. 7. The size, gene content and shape (circular or linear) of mtDNA vary from organism to organism. 4

PowerPoint Presentation:

Introduction Conn….. This organelle produces energy by oxidising organic acids and fats with oxygen by the process of oxidative - phosphorylation and generates oxygen radicals (reactive oxygen species ROS )as a toxic by-product This organelle is also known as ‘ POWER HOUSE OF CELL’ 5

Mitochondria are Passed from Mother to Offspring:

Mitochondria are Passed from Mother to Offspring In most animals father and mother each contribute the same number of chromosomes to the zygote. But there are thousands of mitochondria per egg cell, and only a few in the sperm. And once the sperm enters the egg, those sperm mitochondria are usually destroyed. The zygote ends up filled with mitochondria from the egg, therefore the zygote inherits the maternal mitochondrial DNA. 6

PowerPoint Presentation:


PowerPoint Presentation:

Maternal Effect/Maternal Influence Offspring phenotype under control of nuclear gene product present in the egg Genetic information of mother used to produce products present in the egg cytoplasm - Snail Limnaea peregra shell coiling is an example 8

Snail Limnaea peregra Shell Coiling:

Snail Limnaea peregra Shell Coiling 9 Hermaphroditic snails Some shells have right-handed Dextral (DD or Dd) coiling while others have left-handed Sinistral (dd)coiling Reciprocal crosses (reverse mail and female genotypes) of true-breeding snails Offspring phenotype depends upon maternal genotype—not maternal phenotype -Studied by Sturtevant

PowerPoint Presentation:

10 10

PowerPoint Presentation:

11 Kappa in Paramecium Certain strains of P. aurelia are called killer strains because they release paramecin, a substance toxic to sensitive strains Paramecin produced by kappa particles (100-200 per cell) that replicate in cytoplasm Kappa particles contain DNA and protein and require a nuclear gene (K, “little k” strains are sensitive) for maintenance Kappa particles are bacterialike and may contain temperate phage

PowerPoint Presentation:

12 CO 2 sensitivity Flies fail to recover from CO 2 anesthetization (permanently paralyzed) Sensitivity due to presence of virus called sigma Transfer to other insect species unsuccessful, suggesting Drosophila genes essential for its continued propagation/function Sex ratio in D. bifasciata and D. willistoni Some flies produce offspring at an altered sex ratio Mostly female at below 21 degrees Celsius Trait transmitted only to daughters Agent shown to be a protozoan that is lethal only to males And protozoan may have a virus that is actually responsible… Infective Particles in Drosophila

Cytoplasmic male sterility (CMS):

Cytoplasmic male sterility (CMS) 13 Cytoplasmic Male Sterility Determined by Cytoplasm, Result of mutation in mitochondrial genome. CMS is a maternally inherited trait that is often associated with open reading frames (ORFs) found in mitochondrial genomes. CMS can arise spontaneously in breeding lines, as a result of wide crosses or the interspecific exchange of nuclear and cytoplasmic genomes, or following mutagenesis.

PowerPoint Presentation:

14 Particularly in maize DNA reside in mitochondria and may be located in a plasmid like element. Since mother contributes the cytoplasm to the offspring, the sterility is transferred to the F1. CMS Cont….

CMS Utilization:

CMS Utilization 15 It provides a possible mechanism of pollination control in plants to permit the easy production of commercial quantities of hybrid seeds. It consists of a male sterile line (the A-line), an isogenic maintainer line (The B line), and if necessary also restore line (the R-line). A lines are developed by back-crossing selected B-lines to a CMS A-line for 4 – 6 times to generate a new A-line. B and R-lines are developed by similar back cross procedures using a CMS R-line as female in the original cross and a new line as the recurrent parent in 4 – 6 backcrosses. CMS is used in Hybrid seed Production viz., Pearl millet, Maize, Sorghum, Cotton etc.

pokyness in Neurospora:

pokyness in Neurospora Cytoplasmic/maternal inheritance Maternal poky x paternal wt  all poky Material wt x paternal poky  all wt Loss of several cytochromes Hyphae fusions between poky and wt produce heterokaryons (two nuclei) with mitochondria from both parental cells Begins with normal phenotype Become progressively more abnormal ( poky ) poky is a suppressive mutation Mechanism not clear (loss/modification of wt mitochondria) 16

PowerPoint Presentation:

Saccharomyces petite Mutations 17 petite mutations give rise to small colonies Aerobic respiration blocked Live anaerobically S. cerevisiae is a facultative anaerobe Two types Segregational petites encoded by nuclear genes showing Mendelian inheritance cytoplasmic transmission pattern petites Neutral petites demonstrate (give all wt offspring when crossed to wt) Suppressive petites (behave like poky in Neurospora)

Significance in Plant Breeding:

Significance in Plant Breeding Cytoplasmic Inheritance has been useful in explaining the role of various Cytoplasmic Organelles in the transmission of characters in different Organisms. Studies of cytoplasmic inheritance have played key role in mapping of mitochondrial genome in several species, vis., yeasts, clamydomonas, maize, human etc. Development of cytoplasmic male sterility. 18

PowerPoint Presentation:

19 Thank U 19

authorStream Live Help